Communication: First observation of ground state I(2P3/2) atoms from the CH3I photodissociation in the B-band

The photodissociation of CH3I in the second absorption band (the B-band) has been studied at the wavelength 199.11 nm, coincident with the 3(0)(1) R-3(1)(E) <- (X) over tilde ((1)A(1)) CH3I vibronic transition, using a combination of slice imaging and resonance enhanced multiphoton ionization detection of the CH3 fragment. The kinetic energy and angular distributions of the recoiling CH3 fragment confirm a major predissociation dynamics channel as a result of the interaction between the bound R-3(1) Rydberg state and the repulsive (3)Lambda(1)(E) state - ascribed to the A-band - yielding CH3 fragments in correlation with spin-orbit excited I*(P-2(1/2)) atoms. In addition, first evidence of a non-negligible population of ground state I(P-2(3/2)) atoms in the CH3 fragment slice images, suggests a secondary predissociation mechanism via interaction between the R-3(1) Rydberg state and the repulsive Lambda-band (1)Q(1) state. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3613656]